1. Field of the Invention
The present invention relates to a vehicle headlamp equipped with a so-called projector-type lamp unit.
2. Related Art
In general, a vehicle headlamp is provided with a lamp room formed by a lamp body and a translucent cover attached to a front end opening of the lamp body, the lamp room accommodating a lamp unit having an optical axis extending in the longitudinal direction of a vehicle. Disclosed in JP-A-63-314701 is a projector-type lamp unit as one type of the lamp unit.
In the projector-type lamp unit, a projection lens is disposed on an optical axis of the projector-type lamp unit, and a light source is disposed behind a rear focus point of the projection lens. Light from the light source onto a reflector is reflected so as to direct to an area close to the optical axis. As the projection lens, a plano-convex lens is used. In the plano-convex lens, a front surface is a convex curved surface and a rear surface is a plane.
However, the projection lens has problems described below since a plane constituting its rear surface is orthogonal to an optical axis.
In general, a vehicle headlamp is arranged at the front end of a vehicle, so that its translucent cover often has a surface profile tilted upward along a vehicle profile. A projection lens of the lamp unit is constituted by a plane whose rear surface is orthogonal to an optical axis thus it is impossible to arrange the projection lens along the translucent cover. This results in a larger depth dimension of a lamp room accommodating the lamp unit.
Another problem is that, when the lamp unit is observed through the translucent cover, only its projection lens appears in the front direction of the vehicle, which lacks a novel design of the headlamp.